GCN Circular 32837
Subject
GRB 221022B: AstroSat CZTI detection
Date
2022-10-25T01:57:14Z (2 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), G. Waratkar (IITB), A.
Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka
University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report
on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed the detection of a long GRB 221022B which was
also detected by Fermi GBM (GCN 32820), AGILE (Casentini et al., GCN
32822) and Swift/BAT-GUANO (Gayathri et al., GCN 32823).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2022-10-22 22:56:11.50 UTC. The measured peak count
rate associated with the burst is 1613 (+72, -78) counts/s above the
background in the combined data of all quadrants, with a total of 14862
(+774, -850) counts. The local mean background count rate was 494 (+2,
-3) counts/s. Using cumulative rates, we measure a T90 of 31 (+5, -4) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve peaks at 2022-10-22
22:56:10.86 UTC. The measured peak count rate is 2187 (+97, -105)
counts/s above the background in the combined Veto data of all
quadrants, with a total of 18217 (+1046, -1027) counts. The local mean
background count rate was 1575 (+3, -4) counts/s. We measure a T90 of 27
(+4, -6) s from the cumulative Veto light curve.
CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, URSC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project.